Bereaved animals grieve – if their lifestyle allows it

WHETHER animals comfort dying comrades and show signs of grieving for the dead may depend on where they live, as well as on how compassionate they are.

Many primates carry the bodies of dead infants around with them for days or even weeks. Peter Fashing of California State University in Fullerton and colleagues have observed similar behaviour in a band of over 200 geladas (Theropithecus gelada), monkeys related to baboons, living on alpine grasslands in Ethiopia. Between 2007 and 2010 they saw 14 females carrying dead infants. Some abandoned the corpses within hours, but one female kept one for 48 days even though the flesh had rotted away from the skull (American Journal of Primatology, DOI&colon; 10.1002/ajp.20902).

When Fashing looked at the groups of primates that have been seen carrying bodies for days at a time, he noticed that they all live in “somewhat extreme environments for primates”. The geladas, along with corpse-carrying Japanese macaques and mountain gorillas, live in cold regions where decay is slow, while the chimpanzee group that engages in prolonged carrying lives in an arid region where bodies would quickly mummify.

Fashing thinks that animals that do not carry dead infants, or only do so for a short time, are no less sad about their bereavement. Instead, decay forces them to abandon the bodies sooner.

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The idea is plausible, says Jim Anderson, a primatologist at the University of Stirling, UK. “Cold would slow down the corpse’s decay, so the mother would treat it as if it was still alive.”

Fashing’s team also watched the geladas leave a sick mother and her infant behind to die when they left in search of food. By contrast, captive chimpanzees have been seen caring for a dying companion. This might be because chimps are more compassionate than geladas, or because the chimps had food nearby and didn’t have to wander off.

However, both the chimp and the gelada observations are just one incident, cautions Alison Jolly of the University of Sussex, UK, so it can’t tell us whether geladas really behave differently.